![]() Downloaded from Applied Sciences directorate (2006). Green shades represent vegetation, magenta and brown represent bare soil, black represent water bodies, recent lava flows of shadows, cyan shades represent snow, and white represents clouds. False color composite of Landsat bands 7, 4, and 2. (b–d) Source: NASA GeoCover circa 1990 Landsat images. On the far left and far right, in dark green, natural riparian ecotones can be detected along the rivers. (d) Human-related ecotones resulting from deforestation (in pink) in the Amazon Basin, Brazil. Note also the sharper ecotones in areas where lava has flowed. Ecotones vary over different slopes and elevations. (c) Natural and human-made ecotones on Hawaii’s big island. (b) Altitudinal ecotones between vegetation belts in Mt. True color composite of MODIS satellite images. Source: NASA Blue Marble Next Generation, August 2004. ![]() (a) Ecotones in the Sahel region of Africa (see text). Satellite images showing a variety of natural and human-generated ecotones at several spatial scales. Ecotonal regions show a diversity of boundary types that range from natural boundaries (e.g., altitudinal and latitudinal transitions) to human-generated ecotones, sometimes termed anthropogenic ecotones (e.g., forest clear-cut edges or urban ecotones) ( Lloyd et al., 2000), as shown in Fig. As suggested by Odum (1953), they do not simply represent a boundary or an edge the concept of an ecotone assumes the existence of active interaction between two or more ecosystems with properties that do not exist in either of the adjacent ecosystems. These areas are sometimes considered to be dynamic zones of interaction between communities, which are unstable over time ( Kent et al., 1997). Ecotones can occur in both terrestrial and aquatic systems, and cover several spatial scales, from large spatial-scale ecotones, where biomes meet to local-scale transitions, such as mountain treelines ( Gosz, 1993 see Fig. The definition often relates ecotones to more homogenous areas found on both sides of the transition or to the landscape as a whole. These include boundary regions, borders, meeting zones, transitional zones, tension zones, zones of intermingling, and zones of transgression ( Kent et al., 1997). Many different definitions and terms have been used in the literature to describe areas of ecological transition. The origin of the word “ecotone” is in the Greek roots “oikos” (home) and “tonus” (tension). In these transitional regions, the environment rapidly shifts from one type to another based on abiotic (e.g., climatic) and/or biotic (e.g., community structure) factors ( Holland et al., 1991 Kent et al., 1997). They often occur in areas of steep environmental transition, along environmental gradients. Because ecotones are often small in spatial extent and within this small area they are relatively rich in biodiversity, with populations adapted to change, their conservation may be a cost effective strategy.Įcotones are areas where ecological communities, ecosystems, or biotic regions coincide. As populations in ecotones are potentially pre-adapted to changing environments, they may be more resistant to climate change, biotic invasions invasive species and other environmental changes. As such, ecotones deserve high conservation investment, potentially serving as speciation and biodiversity centers. Evidence suggests that ecotones may also be speciation hotspots where new forms evolve. ![]() Various studies have shown that species richness, diversity and abundances tend to peak in ecotonal areas, though exceptions to these patterns occur. They range from mountain treelines to transitions between large biomes and ecoregions (eg, Mediterranean and arid). Ecotones occur at multiple spatial scales and range from natural ecotones between ecosystems and biomes to human-generated boundaries. Kark, in Reference Module in Life Sciences, 2017 AbstractĮcotones are areas of steep transition between ecological communities, ecosystems, and/or ecological regions along an environmental or other gradient.
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